Transmissions with hydraulically operated clutches (e.g., continuously variable transmissions (CVTs)) are well known in the art. When operating such transmissions, it is important to accurately control clutch engagement in order to provide the desired vehicle performance. However, due to tolerances within the clutch valve and errors associated with the controller's ability to command the correct current, the pressure needed to move the clutch's actuator (e.g., a hydraulically actuated piston) to the point at which the clutch plates touch and the clutch begins to transmit torque can vary significantly. As a result, it is often necessary to calibrate transmission clutches to ensure that the proper clutch pressures are being supplied for engaging each clutch.
When performing a clutch calibration, the accuracy of the calibration process may often be impacted by imperfections, inconsistencies and/or other mechanical and relates issues within the transmission. For example, air bubbles/pockets trapped within the hydraulic system can cause a clutch to calibrate to a different current value than the value that will be required once the trapped air has been removed. Similarly, mechanical issues, such as friction between one or more of the clutch components, shifting of one or more of the clutch components at start-up, the lack of or excessive seal wear, burrs on metal components and/or the like, may also result in inaccuracies within clutch calibration values.
Accordingly, a system and method that enhances the operation of a CVT, such as by allowing more accurate clutch calibrations to be performed, would be welcomed in the technology.